Moisture controller



y 20, 1941 H. G. CRAM I 2,242,778

MOISTURE CONTROLLER Filed Aug. 15, 1938 2 Sheets-Sheet l InventorHill-am E Fittarneufls May 20,1941. H. G. cRAM MOISTURE CONTROLLER FiledAug. 15, 1938 2 Sheets-Sheet 2' a Ht't DTI'IEHS Patented May 20, 1 941nois'runs con LLER Hervey G. Cram, Appleton, Wis, gnor to P. D. Gram,Appleton, Wis.

Application August 15, 1938, Serial No. 225,4?29

. Claims.

paper-making is the necessity of. maintaining a uniform predeterminedmoisture content in the sheet as delivered from the paper machine.

It is an established fact that the quality of the finished sheet isenhanced if the moisture content is of the correct amount, and thisratio of moisture to solids is constant. The percentage of moisture inthe sheet affects the strength-surface, flexibility, etc. It alsoafiects the operation of the paper machine, as a sheet over-dried has atendency to snap ofi in the dryers or at the calender stack, resulting,in a considerable loss of machine time; or, if the sheet contains toomuch moisture, it may be blackened in passing the rolls of the calenderstack. Uneven moisture content along the run of the sheet afiects thegen= eral quality so that these variables are carried through to theprinting processes, which result in printing imperfections. Further,anything less than the proper specified moisture content in the sheetwill result in a considerable monetary loss to the paper manufacturer,in that the difierence in the percentage of moisture content in thesheet and a greater specified moisture content, based on the cost of.the finished sheet, is. a direct loss. It is, therefore, one of theprimaryobjects of my present invention to provide a means to regulatethe flow of steam to the dryers of a paper machine, so as to maintainautomatically the specified percentage of moisture content in the sheetas it is being made on the paper machine.

Another salient objectof my invention is to provide means fordetermining the moisture oontent in the sheet by the rate ofcondensation in one or more of the dryend dryers of the drying sectionof a paper machine.

A further important object of my invention is -to provide means forautomatically regulating the flow of steam to the drying rollers of apapermaking machine according to the rate of. condensation in a.specified drying roll.

A still further object of my invention is to provide a simple anddurable means for actuating a steam valve in accordance with the amountof water of condensation being taken from a drying roll.

With these and other objects in view, the invention' consists in thenovel construction, ar-

rangement, and formation of parts, as will be hereinafter morespecifically described, claimed, and illustrated inthe accompanyingdrawings, in which drawings:

Figure 1 is a diagrtic view of a ing my novel device incorporatedtherewith.

Figure 2 is an enlarged, fragmentary, transverse sectional view througha drying roller at the dryend of a paper-g me, showing myim= proveddevice incorporated therewith, the various or wet end thereoi; and rollst, i, ii, ii, it, and M at the rear or dry end thereof. There can be asmany intermediate drying rolls as may be desired,

and, as stated, Figure l is of a diagrannnatic nature.

The paper sheet 82, shown in dot-and-dash lines in the drawing, istrained over. the various rolls in the usual manner, and these rotatingrolls are all connected at their axial centers through couplings it withbranch pipes it! leading from a common steam supplying pipe or header itor from any other suitable source of supply. This header i5 is connectedby means of a pipe it and suitable couplings with a steam delivery pipeii. The pipe it has incorporated in the length thereof a valve id forcontrolling the flow of steam through the pipe it and to the battery ofdrying rolls.

The water oi condenwtion from the various rolls can be removed in amanner similar to that shown in my prior Patents Nos. 1,919,416 and.

2,045,634, issued respectively on July 25, 1933, and

- June 30, 1936. Thus, positioned in each roll is a syphon pipe is,which leads out of the coupling part of the drying section oi apaper-making machine, showfibrous).

the initial dryers I, 2, 3, etc. at the wet end,

. where the sheet is delivered in its wettest condition, will begreatest, decreasing in each successive dryer as thesheet reaches adrier state,

until at the last dryers l and I! the sheet has very nearly reached therequired dryness, and

- the rate of condensation in these dryers is prac-- tically nil undernormal operation.

It is obvious that with a flireclfiow'oi steam decreasing on successivedryers until near the I dry-end dryers i, 8, 9, it, and ii a markedvariation in steam requirement is apparent. This ,variation is efiectedby some variation in the sheet as entering-the driers; that is, thesheet may vary in thickness (weight), or the make-up of the sheet'mayvary in freeness (more or less The more fibrous or free sheet is lessresistant to the evaporation of moisture, and, naturally, the thicker orheavier sheet, containing proportionately more moisture, is more dimcultto dry.

With an excessive drying burden eifected by one or both of thesevariables in the sheet, the first dryers I, 2, 3, etc. will transferthis exce sive drying burden to successive dryers in the section. Thistransfer of drying burden to the dry-end dryers will increase the rateof condensation in these dryers, and this increase is proportional tothe amount of moisture in the sheet at that point. Therefore, byselecting a dryer (such as drying roll 3) at the dry end as a testdryer, and measuring the condensate therefrom as to rate of flow, andproviding a means for transmitting this variation to the control valveil in the steam supply line II, the rate of drying on the completesection of dryers will vary with the variation in the sheet, with theresult that a uniformly dried sheet will be delivered from the dryers.

Referring more particularly to the drying roll 3, it will be seen thatthe condensate is removed continuously therefrom through the syphon pipeI. to a vertical pipe consisting of an upper section 2|, an intermediaterelatively long section 22, and a lower section 23. The upper andintermediate sections are connected through the medium of a desiredsteam trap 24, and the intermediate and lower pipe sections areconnected together through the medium of a desired steam trap 23.

The lower pipe section 23 discharges at a considerably lower pressureinto a hot well, vacuum pump, atmosphere, or the like. The intermediatepipe length 22 has incorporated therein, at a point intermediate itslength, a moisture control 23. J

A pressure relief is provided for the pipe section 2| by means of acommunicating pipe 21,

with a diaphragm pressure differential control valve 23 therein. Thisdifferential control valve 23 has one side of its diaphragm equalized asto pressure with the supply pipe l4, and the other side equalized as topressure with the condensate return pipe section 2|, by means of pipes23 and 33. The adjustment of differential in pressure across the valveis by means of the spring in the valve, which assures a constantpredetermined pressure difl'erential across the dryer.

The trap 24 is provided in the condensate return pipe section 2| toprevent passage of steam and to also prevent the dryer pressure frombeing transferred to the moisture controller 26. The

moisture controller 23 is in the nature of a valve, and is provided withan orifice 31, the size of which is controlled by means of an adjustablehand wheel 32, actuatinga needle valve body. The discharge from themoisture controller 26 is to the trap 25, which effects a constantpressure on the discharge of the moisture controller 26. A communicatingpipe 33 between the intake and discharge of the moisture controller 26equalizes the differential across the moisture controller 26, except asaffected by the hydrostatic head of the column of condensate held backby the moisture controller 2%.

- The pressure head of the column of condensate above the moisturecontroller 26 is communicated to the diaphragm of the pilot valve 36through pipe 33, which regulates the pressure to the diaphragm 36 of thecontrol valve it in the steam supply pipe ii.

The upper connection of pipe 33 to the pipe section 22 is purposely highin order to avoid by-passing the condensate past the moisture conthediaphragm 36. However, the pipe 31 has incorporated in the lengththereof the pilot valve 34, which includes the valve body 38 movabletoward and away from its seat according tothe pressure of the column ofthe water of condensate in the pipe 22.

It is to be noted that the control valve I8 is normally held on its seatby the spring 39 thereof, bearing on the diaphragm 36, and that airpressure working on the diaphragm 36 controls the opening of the controlvalve l8. The air supply pipe 31 can be provided with a strainer 43 anda reducing valve 4 I. The valve 4| reduces the pressure to a constantpredetermined amount, which, in the present instance, has been set tofifteen pounds. Thus, the pressure leading toward the valve body 33 isconstant. An orifice 42 is provided on the righthand side of thepressure reducing valve 4|, and this orifice is equal in area to theorifice in the pilot valve 34 when the pilot valve is in its wideopenposition, that is, when the valve body 38 is entirely oflf its seat.When in this position, the pressure is zero between the orifice l5 andthe diaphragm 36 of the steam control valve.

The injection of the valve 38. into the pilot valve reduces thedischarge to the atmosphere (pipe 43) proportionately, and raises thepressure in the pipes leading to the diaphragm 36, which results in theforcing of the stem of the control valve l3 downwardly. This opens thecontrol valve I3 againstthe action of its spring variation in the sheetentering the dryers, such as an increase in the weight of the sheet,causes a part of the drying burden to be transferred to the successivedryers in'the section, so that the dry-end dryers are forced to condensea greater amount of steam. This additional rate of flow of condensatewill raise the head of the column of condensate in pipe 22 above theorifice of the moisture controller 26; and this pressure head will becommunicated through pipe 35 to the pilot valve 34, to the control valvel8, opening the valve l8 and allowing a proportional increase of steamto be supplied to the entire dryer section, suflicient to dry theheavier sheet to the same percentage of dryness as the previous normalweight sheet.

A decrease in the weight of the sheet reduces the head of the column tocondensate, and this decrease in pressure head is communicated throughthe pilot valve 34 to the control valve l8, effecting a proportionalclosing thereof, This reduces the rate of dryness on the initial dryers,thereby forcing the subsequent dryers to assume their proper share ofthe drying.

Obviously, my invention can take various forms, and, hence, the formshown and described is merely to be taken as illustrative of one form ofmy invention.

Changes in details may be made tion, but what I claim as new is 1. In apaper-making machine, a drying section including a plurality of dryingrolls, a header pipe for steam, a pipe for supplying steam to saidheader, a control valve in the supply pipe, means for operating saidvalve by fluid pressure, a pilot valve for controlling the flow of fluidto the first-mentioned valve, means for supplying steam to the rollsfrom said header pipe, a header for the water of condensation, pipes forreceiving water of eondensation from the rolls and conducting the sameto the header for the water of condensation, means for operating thepilot valve from the head of water in one of the pipes receiving waterof condensation from one of the rolls, and means for governing the flowof water of condensation through said pipes.

2. In a paper-making machine, a drying section including a plurality ofdrying rolls, means for supplying steam to all of said rolls including aheader and a steam supply pipe leading to the header, a valve in saidsteam supply pipe, means for removing water of condensation from one ofsaid rolls including a vertically disposed trolling the flow of water ofcondensation in the vertical pipe.

3. In a paper-making machine, a drying section including a plurality ofdrying rolls, means for supplying steam to all of said rolls including aheader and a steam supply pipe leading to the header, a valve in saidsteam supply pipe,

without departing from the spirit or scope of my inven-w means forremoving water of condensation from one of said rolls including avertically disposed pipe, steam traps in said last-mentioned pipe, meansfor operating the valve for the steam supply pipe by fluid pressure, apilot valve for controlling the flow of fluid pressure to saidlastnientioned means, means for operating the pilot valve by the head ofwater in the vertical pipe between the steam traps, and manuallycontrolled means for governing the flow of water of condensation in thevertical pipebetween the steam traps.

4. In a paper-making machine, a drying section including a plurality ofdrying rolls, means for supplying steam to the rolls, valve means forregulating the supply of steam to the rolls, and means for regulatingthe moisture content in the paper sheet leaving said rolls according tothe rate of condensation of the steam supplied to said rolls including acondensate-receivingmember, means for governing the rate or flow of thecondensate from said member, and means actuated in response tovariations in the head of condensate in the condensateand means forcontrolling the valve in the steam supply delivery pipe according to thehead of water of condensation in said measuring member.

HERVEY G. CRAM.

